Process for making polybutylene terephthalate (pbt) from polyethylene terephthalate (pet)

ABSTRACT

The invention relates to a process for making modified polybutylene terephththalate random copolymers from a polyethylene terephthalate component. The invention relates to a three step process in which a diol component selected from the group consisting of ethylene glycol, propylene glycol, and combinations thereof reacts with a polyethylene terephthalate component under conditions sufficient to depolymerize the polyethylene terephthalate component into a first molten mixture; and where the first molten mixture is combined with 1,4-butanediol under conditions that create a second molten mixture that is subsequently placed under subatmospheric conditions that produce the modified polybutylene terephthalate random copolymers. The invention also relates to compositions made from the process.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application Ser.Nos. 60/777,901 filed on Mar. 1, 2006, and U.S. Provisional ApplicationSer. Nos. 60/820,467 filed on Jul. 26, 2006, and U.S. Non-provisionalapplication Ser. No. 11/626,674, filed on Jan. 24, 2007, which areincorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

Polyethylene terephthalate (also referred to as “PET”) is a polyester ofterephthalic acid and ethylene glycol and can be obtained by thepolycondensation of dimethyl terephthalate with ethylene glycol, andalso terephthalic acid with ethylene glycol. PET exists both as anamorphous (transparent) and as a semi-crystalline (opaque and white)thermoplastic material. Generally, it has useful chemical resistance tomineral oils, solvents and acids but not to bases. Semi-crystalline PEThas good strength, ductility, stiffness and hardness. Amorphous PET hasbetter ductility but less stiffness and hardness. PET is used to makebottles for soft drinks and other household, consumer and industrialproducts.

Unfortunately, despite recycling efforts, billions of pounds of PET arestill dumped into landfills annually all over the world. Other PET thatis not reused is incinerated. The substantial amount of PET that isdisposed into landfills creates significant waste. The incineration ofPET wastes significant resources that could be used more effectively.

Thermoplastic molding compositions based on polybutylene terephthalate(also referred to as “PBT”) and fillers are used in variousapplications. Although conventional PBT-filler molding compositions areuseful to many customers, conventional PBT-filler molding compositionsgenerally cannot be made from recycle sources of PBT due to the lack ofavailability of PBT recycle streams. PET, unlike PBT, is made in muchlarger quantities and is partially recovered from consumer wastes. IfPET (scrap) materials could be converted to PBT and converted intouseful molding compositions, then there would exist a valuable way tomeet the unmet need to effectively use underutilized scrap PET in PBTthermoplastic molding compositions.

U.S. Pat. No. 5,451,611 teaches a process for converting wastepoly(ethylene terephthalate) to either poly(ethylene-co-butyleneterephthalate) or poly(butylene terephthalate) (PBT) by reaction with1,4-butanediol. In discussing the prior art, U.S. Pat. No. 5,451,611indicates that in most of the processes it cites, the undesirablebyproduct diethylene glycol is formed which contaminates the finalproduct and has to be removed by purification before the recoveredproducts can be reused again. A principal object of U.S. Pat. No.5,451,611 was to provide a process for converting poly(ethyleneterephthalate) waste directly to another high value polymer withoutbreaking down the poly(ethylene terephthalate) to its constituentmonomers or oligomers. The patent discloses numerous examples in which avariety of polymers have a diol incorporated at various amounts. Example11 shows a PBT polymer being formed with a complete replacement ofethylene glycol with 1,4-butanediol.

U.S. Pat. No. 5,266,601 teaches a process for making “PBT” from PET byreacting PET with 1,4-butanediol. A principal object of U.S. Pat. No.5,266,601 was to produce PBT containing less than 1.0 wt. % units ofethylene glycol from PET scrap. Another principal objective of U.S. Pat.No. 5,266,601 was to develop a process that facilitates the reduction ofTHF generated in the process as much as possible to the extent that thisPBT is economically competitive with PBT obtained from monomers. U.S.Pat. No. 5,266,601 emphasizes the production of PBT having ethyleneglycol groups in an amount that is less than 1 wt. %. U.S. Pat. No.5,266,601 discloses that “[a]ny diethylene glycol units in the startingPET are also eliminated as completely as possible” (Col. 3, 11 37-38).The patent discloses “adding only enough 1,4BD [1,4-butanediol] to thePET as is necessary to yield a mixture that can be processed well at thereaction temperature.” The patent discloses that, depending on the PETused “up to 1.0 mol 1,4-BD per mol PET” can be used. In the instanceswhere compositions contain more than 1 wt. % ethylene glycol, U.S. Pat.No. 5,266,601 presents these compositions in comparative examples. Suchcompositions are described as having “yellowish” and “slightlyyellowish” colors, respectively. It is not clear what standard is usedin U.S. Pat. No. 5,266,601 to determine the weight percent reported, asthe weight percent can reasonably be defined in as follows: (i) adivalent ethylene radical remaining after removal of hydroxyl groupsfrom ethylene glycol, or (ii) a divalent radical remaining after removalof terminal hydrogen atoms from ethylene glycol. Each moeity hasdifferent molecular weight and, as such, each moiety can produce adifferent value.

Japanese laid-open application 2005-89572 teaches a method for producingpolybutylene terephthalate by transesterifying bis(2-hydroxyethyl)terephthalate with 1,4-butanediol in the presence of atransesterification reaction catalyst under the pressure of 1-54 kPa ata final temperature ranging from 200-230° C. and then subjecting thereaction product to polycondensation. In one embodiment, thebis(2-hydroxyethyl) terephthalate is obtained by depolymerizingpolyethylene terephthalate with excessive ethylene glycol, and purifyingthe depolymerized product. The patent teaches that transesterifyingbis(2-hydroxyethyl)terephthalate with 1,4-butanediol under reducedpressure imparts favorable results.

Unfortunately, such documents do not meet the long felt need of improveduse of PET scrap that is ordinarily incinerated or buried in landfills.U.S. Pat. No. 5,451,611, for instance, does not teach effectiveprocesses that enable PET to be able to be broken down into itsconstituent monomers or oligomers—a feature that is sometimes requiredby commercial considerations. U.S. Pat. No. 5,451,611 does not providemeaningful guidelines for making compositions functionally similar toPBT containing ethylene glycol in amounts other than trace amounts andwhich exhibit melting temperatures that are higher than those shown inits examples. Similarly, U.S. Pat. No. 5,266,601 does not providemeaningful details about how to make effective PBT materials withethylene glycol in amounts more than 1.0 wt. % or with other residuesthat can be found in some PET scrap. Also, U.S. Pat. No. 5,266,601 doesnot disclose to relatively more versatile processes that can use excess1,4-butanediol, relative to the PET scrap used or that do not requirethat the diethylene glycol be “eliminated as completely as possible.”Known technology relating to utilizing PET as scrap materials for makingPBT-like materials, in other words, does not provide meaningfulsolutions that solve the long felt need of new processes for betterutilizing PET scrap that is ordinarily incinerated or buried inlandfills.

For the foregoing reasons, there is a need to develop improved processesthat utilize PET.

For the foregoing reasons, there is a need to develop new processes formaking PBT random copolymers having useful performance properties.

For the foregoing reasons, there is a need to develop new articles frommolding compositions that utilize PBT derived from PET and that haveuseful performance properties.

BRIEF DESCRIPTION OF THE INVENTION

The invention relates to a process comprising:

(a) reacting (i) a polyethylene terephthalate component selected fromthe group consisting of polyethylene terephthalate and polyethyleneterephthalate copolymers with a diol component selected from the groupconsisting of ethylene glycol, propylene glycol, and combinationsthereof, in a reactor at a pressure that is at least atmosphericpressure in the presence of a catalyst component at a temperatureranging from 190° to 250° C., under an inert atmosphere, underconditions sufficient to depolymerize the polyethylene terephthalatecomponent into a first molten mixture containing components selectedfrom the group consisting of oligomers containing ethylene terephthalatemoieties, oligomers containing ethylene isophthalate moieties, oligomerscontaining diethylene terephthalate moieties, oligomers containingdiethylene isophthalate moieties, oligomers containing trimethyleneterephthalate moieties, oligomers containing trimethylene isophthalatemoieties, covalently bonded oligomeric moieties containing at least twoof the foregoing moieties, ethylene glycol, propylene glycol andcombinations thereof; wherein the polyethylene terephthalate componentand the diol component are combined under agitation;

(b) adding 1,4-butanediol to the first molten mixture in a reactor inthe presence of a catalyst component at a temperature ranging from 190°C. to 240° C., under conditions that are sufficient to form a secondmolten mixture containing a component selected from the group consistingof oligomers containing ethylene terephthalate moieties, oligomerscontaining ethylene isophthalate moieties, oligomers containingdiethylene terephthalate moieties, oligomers containing diethyleneisophthalate moieties, oligomers containing trimethylene terephthalatemoieties, oligomers containing trimethylene isophthalate moieties,oligomers containing butylene terephthalate moieties, oligomerscontaining butylene isophthalate moieties, covalently bonded oligomericmoieties containing at least two of the foregoing moieties,1,4-butanediol, propylene glycol, ethylene glycol, and combinationsthereof; and

(c) increasing the temperature of the second molten mixture undersubatmospheric conditions and agitation to a temperature from 240° C. to260° C., thereby forming a modified random polybutylene terephthalatecopolymer containing at least one residue derived from the polyethyleneterephthalate component.

In one embodiment, the invention relates to a composition comprising anon-yellow modified polybutylene terephthalate random copolymer madefrom the process of wherein the modified polybutylene terephthalaterandom copolymer has an intrinsic viscosity that is more than 0.55 dL/gand wherein the isophthalic acid is present in an amount that is morethan 0.85 wt. % or from 0.2 wt. % to 3 wt. %.

These and other features, aspects, and advantages of the presentinvention will become better understood with reference to the followingdescription and appended claims.

DETAILED DESCRIPTION OF THE INVENTION

The invention is based on the discovery that it is now possible to makea material that is derived from scrap polyethylene terephthalate thatperforms similarly to “virgin PBT” (PBT that is derived from monomers)in a novel and effective process. Unlike conventional methods for makingvirgin PBT, the PBT component made by the invention contains, inaddition to other materials, ethylene glycol and isophthalic acid groups(components that are not present in virgin PBT). Despite producing a PBTthat is structurally different from PBT used in known compositions,e.g., thermoplastic molding compositions, the PBT component of theinvention exhibits similar performance properties as a moldingcomposition containing virgin PBT. The compositions can also containdiethylene glycol groups.

Other than in the operating examples or where otherwise indicated, allnumbers or expressions referring to quantities of ingredients, reactionconditions, and the like, used in the specification and claims are to beunderstood as modified in all instances by the term “about.” Variousnumerical ranges are disclosed in this patent application. Because theseranges are continuous, they include every value between the minimum andmaximum values. Unless expressly indicated otherwise, the variousnumerical ranges specified in this application are approximations.

All molecular weights in this application refer to number averagemolecular weight obtained with the polystyrene standard. Details of thetechnique include the following items: (i) Instrument: Waters 2695separation module; (ii) Detector: Waters 2487 Dual AbsorbanceUltraviolet Detector@273 and 295 nanometers and Waters 410refractomerrefractometer; (iii) Mobile phase: 5% HFIP 95% chloroform;(iv) GPC columns: Polymer Labs PL HFIP gel 250×4.6 mm, (v) Flow rate:0.3 ml/min; (vi) Injection volume 10 μl; (vii) Polystyrene standards:Polymer Lab's Easical PS-1, 580-7,500,000 Da.

For the sake of clarity, the terms terephthalic acid group, isophthalicacid group, butanediol group, ethylene glycol group in formulas have thefollowing meanings. The term “terephthalic acid group” (R′) in acomposition refers to a divalent 1,4-benzene radical (-1,4-(C₆H₄)—)remaining after removal of the carboxylic groups from terephthalic acid.The term “isophthalic acid group” (R″) refers to a divalent 1,3-benzeneradical (−(-1,3-C₆H₄)—) remaining after removal of the carboxylic groupsfrom isophthalic acid. The “butanediol group” (D) refers to a divalentbutylene radical (—(C₄H₈)—) remaining after removal of hydroxyl groupsfrom 1,4-butanediol. The term “ethylene glycol group” (D′) refers to adivalent ethylene radical (—(C₂H₄)—) remaining after removal of hydroxylgroups from ethylene glycol. With respect to the terms “terephthalicacid group,” “isophthalic acid group,” “ethylene glycol group,”“butanediol group,” and “diethylene glycol group” being used in othercontexts, e.g., to indicate the weight % of the group in a composition,the term “isophthalic acid group(s)” means the group having the formula(—O(CO)C₆H₄(CO)—), the term “terephthalic acid group(s)” means the grouphaving the formula (—O(CO)C₆H₄(CO)—), the term diethylene glycol groupmeans the group having (—O(C₂H₄)O(C₂H₄)—), the term “butanediolgroup(s)” means the group having the formula (—O(C₄H₈)—), and the term“ethylene glycol groups(s)” means the group having formula (—O(C₂H₄)—).

The modified polybutylene terephthalate component derived frompolyethylene terephthalate (PET-derived modified PBT component) is (1)is derived from a polyethylene terephthalate component selected from thegroup consisting of polyethylene terephthalate and polyethyleneterephthalate copolymers and (2) has at least one residue derived fromthe polyethylene terephthalate component. In one embodiment, themodified polybutylene terephthalate component can further be derivedfrom a biomass-derived 1,4-butanediol, e.g. corn derived 1,4-butanediolor a 1,4-butanediol derived from a cellulosic material.

The term “biomass” means living or dead biological matter that can bedirectly or subsequently converted to useful chemical substances thatare ordinarily derived from non-renewable hydrocarbon sources. Biomasscan include cellulosic materials, grains, starches derived from grains,fatty acids, plant based oils, as well as derivatives from these biomassexamples. Examples of useful chemical substances include and are notlimited to diols; diacids; monomers used to make diols or acids, e.g.,succinic acid; monomers used to make polymers; and the like. Biomassbased 1,4-butanediol can be obtained from several sources. For instance,the following process can be used to obtain biomass-based1,4-butanediol. Agriculture based biomass, such as corn, can beconverted into succinic acid by a fermentation process that alsoconsumes carbon dioxide. Such succinic acid is commercially availablefrom several sources such as from Diversified Natural Products Inc.under the trade name “BioAmber™”. This succinic acid can be easilyconverted into 1,4-butanediol by processes described in severalpublished documents such as in U.S. Pat. No. 4,096,156, incorporatedherein in its entirety. Bio-mass derived-1,4-butanediol can also beconverted to tetrahydrofuran, and further converted topolytetrahydrofuran, also known as polybutylene oxide glycol. Anotherprocess that describes converting succinic acid into 1,4-butanediol isdescribed in Life Cycles Engineering Guidelines, by Smith et al., asdescribed in EPA publication EPA/600/R-1/101 (2001).

The residue derived from the polyethylene terephthalate component, whichis present in the modified polybutylene terephthalate component can beselected from the group consisting of ethylene glycol groups, diethyleneglycol groups, isophthalic acid groups, antimony-containing compounds,germanium-containing compounds, titanium-containing compounds,cobalt-containing compounds, tin-containing compounds, aluminum,aluminum salts, 1,3-cyclohexane dimethanol isomers, 1,4-cyclohexanedimethanol isomers, the cis isomer of 1,3-cyclohexane dimethanol, thecis isomer of 1,4-cyclohexane dimethanol, the trans isomer of1,3-cyclohexane dimethanol, the trans isomer of 1,4-cyclohexanedimethanol, alkali salts, alkaline earth metal salts, including calcium,magnesium, sodium and potassium salts, phosphorous-containing compoundsand anions, sulfur-containing compounds and anions, naphthalenedicarboxylic acids, 1,3-propanediol groups, and combinations thereof.Depending on factors such as polyethylene terephthalate and polyethyleneterephthalate copolymers, the residue can include various combinations.In one embodiment, for instance, the residue includes mixtures ofethylene glycol and diethylene glycol. In another embodiment, theresidue includes mixtures of ethylene glycol, diethylene glycol andisophthalic acid. In another embodiment, the residue derived frompolyethylene terephthalate further includes cis isomers of1,3-cyclohexanedimethanol and 1,4-cyclohexanedimethanol, the transisomer of 1,3-cyclohexanedimethanol, the trans isomer of1,4-cyclohexanedimethanol and combinations thereof. And in anotherembodiment, the residue can be a mixture of ethylene glycol, diethyleneglycol, and isophthalic acid groups, cis isomers ofcyclohexanedimethanol, trans isomers of cyclohexanedimethanol, andcombinations thereof. In one embodiment, the residue derived frompolyethylene terephthalate includes mixtures of ethylene glycol,diethylene glycol, and a cobalt-containing compound. Suchcobalt-containing compound mixture can also contain isophthalic acidgroups.

In one embodiment, for instance, the modified polybutylene terephthalatecomponent derived from polyethylene terephthalate (PET-derived modifiedPBT component, or modified polybutylene terephthalate copolymerscontaining residues derived from polyethylene terephthalate) that ismade by the process of the invention is a random copolymer containinggroups selected from the following groups:

where R′ is a terephthalic group (-1,4-(C₆H₄)—);

R″ is an isophthalic acid group (-1,3-(C₆H₄)—);

D is a butanediol group (—(C₄H₈)—)

D′ is an ethylene glycol group (—(C₂H₄)—).

The modified polybutylene terephthalate copolymers containing residuesderived from polyethylene terephthalate can also contain diethyleneglycol groups.

The amount of the ethylene glycol groups, diethylene glycol groups, andthe isophthalic groups in the polymeric backbone of the modified PBTcomponent can vary. The PET-derived modified PBT component ordinarilycontains isophthalic acid groups in an amount that is at least 0.1 mole% and can range from 0 or 0.1 to 10 mole % (0 or 0.07 to 7 wt. %). ThePET-derived modified PBT component ordinarily contains ethylene glycolin an amount that is at least 0.1 mole % and can range from 0.1 to 10mole %. (0.02 to 2 wt. %). In one embodiment, the PET-derived modifiedPBT component has an ethylene glycol content that is more than 0.85 wt.%. In another embodiment, compositions made by our process can containethylene glycol is present in an amount ranging from 0.1 wt. % to 2 wt.%. The modified PBT component can also contain diethylene glycol in anamount ranging from 0.1 to 10 mole % (0.04 to 4 wt. %). The amount ofthe butanediol groups is generally about 98 mole % and can vary from 95to 99.8 mole % in some embodiments. The amount of the terephthalic acidgroups is generally about 98 mole % and can vary from 90 to 99.9 mole %in some embodiments.

Unless otherwise specified, all molar amounts of the isophthalic acidgroups and or terephthalic acid groups are based on the total moles ofdiacids/diesters in the composition. Unless otherwise specified, allmolar amounts of the butanediol, ethylene glycol, and diethylene glycolgroups are based on the total moles of diol in the composition. Theweight percent measurements stated above are based on the wayterephthalic acid groups, isophthalic acid groups, ethylene glycolgroups, and diethylene glycol groups have been defined herein.

The total amount of materials of the polyethylene terephthalatecomponent residue in the modified polybutylene terephthalate randomcopolymer can vary. For instance, mixtures can be in an amount rangingfrom 1.8 to 2.5 wt. %, or from 0.5 to 2 wt. %, or from 1 to 4 wt. %. Theethylene glycol, diethylene glycol, and cyclohexanedimethanol groups canbe individually or in combination present in an amount ranging from 0.1to 10 mole %, based on 100 mole % of glycol of the molding composition.The isophthalic acid groups can be present in an amount ranging from 0.1to 10 mole %, based on 100 mole % of diacid/diester in the moldingcomposition.

It has been discovered that when it is desirable to make a polybutyleneterephthalate copolymer having a melting temperature Tm that is at least200° C., the total amount of diethylene glycol, ethylene glycol, andisophthalic acid groups should be within a certain range. As such, inone embodiment, the total amount of the diethylene glycol, ethyleneglycol, and isophthalic acid groups in the modified polybutyleneterephthalate component is more than 0 and less than or equal to 23equivalents, relative to the total of 100 equivalents of diol and 100equivalents of diacid groups in the modified polybutylene terephthalaterandom copolymer. In another suitable embodiment, the total amount ofthe isophthalic acid groups, ethylene glycol groups, and diethyleneglycol groups ranges from 3 and less than or equal to 23 equivalents,relative to the total of 100 equivalents of diol and 100 equivalents ofdiacid groups in the modified polybutylene terephthalate randomcopolymer. In another suitable embodiment, the total amount of theisophthalic acid groups, ethylene glycol groups, and diethylene glycolgroups ranges from 3 and less than or equal to 10 equivalents, relativeto the total of 100 equivalents of diol and 100 equivalents of diacidgroups in the modified polybutylene terephthalate random copolymer. Inanother suitable embodiment, the total amount of the isophthalic acidgroups, ethylene glycol groups, and diethylene glycol groups ranges from10 and less than or equal to 23 equivalents, relative to the total of100 equivalents of diol and 100 equivalents of diacid groups in themodified polybutylene terephthalate random copolymer. In one embodiment,diethylene glycol, ethylene glycol and/or isophthalic acid can be addedduring the process.

It has also been discovered that the total amount of inorganic residuesderived from the polyethylene terephthalate can be present from morethan 0 ppm and up to 1000 ppm. Examples of such inorganic residues canbe selected from the group consisting of antimony-containing compounds,germanium-containing compounds, titanium-containing compounds,cobalt-containing compounds, tin containing compounds, aluminum,aluminum salts, alkaline earth metal salts, alkali salts, includingcalcium, magnesium, sodium and potassium salts, phosphorous-containingcompounds and anions, sulfur-containing compounds and anions, andcombinations thereof. In another embodiment, the amounts of inorganicresidues can range from 250 to 1000 ppm. In another embodiment, theamounts of inorganic residues can range from 500 to 1000 ppm.

The PET component from which the modified polybutylene terephthalaterandom copolymer is made can be in any form that can be used accordingto our invention. Generally, the PET component includes recycle (scrap)PET in flake, powder/chip, film, or pellet form. Before use, the PET isgenerally processed to remove impurities such as paper, adhesives,polyolefin, e.g., polypropylene, polyvinyl chloride (PVC), nylon,polylactic acid and other contaminants. Also, the PET component caninclude PET that is not waste in flake, chip or pellet form. As such,PET that would ordinarily be deposited in landfills can now be usedproductively and effectively. In one embodiment, PET component can alsoinclude other polyesters. The PET component can also include polyestercopolymers. Examples of such materials include polyalkyleneterephthalates that can be selected from polyethylene terephthalate,polycyclohexane terephthalate, copolyesters of terephthalate esters withcomonomers containing cyclohexane-dimethanol and ethylene glycol,copolyesters of terephthalic acid with comonomers containingcyclohexanedimethanol and ethylene glycol, polybutylene terephthalate,poly-xylylene terephthalate, polydianol terephthalates, polybutyleneterephthalate, polytrimethylene terephthalate, polyester naphthalates,and combinations thereof.

In one embodiment, our process (a) reacts (i) a polyethyleneterephthalate component selected from the group consisting ofpolyethylene terephthalate and polyethylene terephthalate copolymerswith a diol component selected from the group consisting of ethyleneglycol, propylene glycol, and combinations thereof, in a reactor at apressure that is at least atmospheric pressure in the presence of acatalyst component at a temperature ranging from 190° to 250° C., underan inert atmosphere, under conditions sufficient to depolymerize thepolyethylene terephthalate component into a first molten mixturecontaining components selected from the group consisting of oligomerscontaining ethylene terephthalate moieties, oligomers containingethylene isophthalate moieties, oligomers containing diethyleneterephthalate moieties, oligomers containing diethylene isophthalatemoieties, oligomers containing trimethylene terephthalate moieties,oligomers containing trimethylene isophthalate moieties, covalentlybonded oligomeric moieties containing at least two of the foregoingmoieties, ethylene glycol, propylene glycol and combinations thereof;wherein the polyethylene terephthalate component and the diol componentare combined under agitation. Then, the process adds 1,4-butanediol tothe first molten mixture in a reactor in the presence of a catalystcomponent at a temperature ranging from 190° C. to 240° C., underconditions that are sufficient to form a second molten mixturecontaining a component selected from the group consisting of oligomerscontaining ethylene terephthalate moieties, oligomers containingethylene isophthalate moieties, oligomers containing diethyleneterephthalate moieties, oligomers containing diethylene isophthalatemoieties, oligomers containing trimethylene terephthalate moieties,oligomers containing trimethylene isophthalate moieties, oligomerscontaining butylene terephthalate moieties, oligomers containingbutylene isophthalate moieties, covalently bonded oligomeric moietiescontaining at least two of the foregoing moieties, 1,4-butanediol,propylene glycol, ethylene glycol, and combinations thereof. The processthen involves increasing the temperature of the second molten mixtureunder subatmospheric conditions and agitation to a temperature from 240°C. to 260° C., thereby forming a modified random polybutyleneterephthalate copolymer containing at least one residue derived from thepolyethylene terephthalate component.

The modified polybutylene terephthalate random copolymer component cancontain a component selected from the group consisting of (1), (2), (3),(4), (5), (6), and combinations thereof; components (1), (2), (3), (4),(5), (6) having the following formulae:

wherein (R′) is a terephthalic acid group (-1,4-(C₆H₄)—);

R″ is an isophthalic acid group (-1,3-(C₆H₄)—);

D is a butanediol group (—(C₄H₈)—);

D′ is an ethylene glycol group (—(C₂H₄)—); and

D″ is a propylene glycol group (—(C₃H₆)—).

This three step embodiment provides an advantageous way for producingmodified PBT random copolymers from PET. The diol component used in step(a) of the three step embodiment can be selected from ethylene glycol,propylene glycol, and combinations thereof. It will be appreciated thatthe molten mixture that forms when the polyethylene terephthalatecomponent is depolymerized can vary, depending on how it isdepolymerized. When the polyethylene terephthalate component isdepolymerized with ethylene glycol and the first molten mixture containsoligomers containing ethylene terephthalate moieties, oligomerscontaining ethylene isophthalate moieties, oligomers containingdiethylene terephthalate moieties, oligomers containing diethyleneisophthalate moieties, covalently bonded oligomeric moieties containingat least two of the foregoing moieties, ethylene glycol, andcombinations thereof. When the polyethylene terephthalate component isdepolymerized with propylene glycol and the first molten mixturecontains oligomers containing ethylene terephthalate moieties, oligomerscontaining ethylene isophthalate moieties, oligomers containingdiethylene terephthalate moieties, oligomers containing diethyleneisophthalate moieties, oligomers containing trimethylene terephthalatemoieties, oligomers containing trimethylene isophthalate moieties,covalently bonded oligomeric moieties containing at least two of theforegoing moieties, ethylene glycol, propylene glycol and combinationsthereof. In another embodiment, the polyethylene terephthalate can bedepolymerized with mixtures of ethylene glycol and 1,4-butane diol. Whenpropylene glycol is used to depolymerize PET, it is understood thateither 1,3 or 1,2 propylene glycol could be used.

The diol component can be present in step (a) at a molar amount that isat least half the amount of ethylene glycol moieties present in thepolyethylene terephthalate component. In one embodiment, the diolcomponent selected from the group consisting of ethylene glycol,propylene glycol, and combinations thereof is present in step (a) at amolar amount that is at least 25% of the amount of ethylene glycolmoieties present in the polyethylene terephthalate component. Thedepolymerization of the polyethylene terephthalate component can becarried out for various times. In one embodiment, the depolymerizationis carried out for at least 25 minutes.

The 1,4-butanediol used during step (b) of the three step embodiment canbe added at a molar amount that is in excess relative to the molaramount of butanediol moieties incorporated into the modifiedpolybutylene terephthalate random copolymer component obtained in step(c). The 1,4-butanediol can be added in step (b) in a molar amount thatis in at least 1.2 times molar excess relative to the molar amount ofbutanediol moieties incorporated into the modified polybutyleneterephthalate random copolymer component obtained in step (c).

During the process the compounds used in the process can be reusedand/or collected. In one embodiment, the (1) diol component selectedfrom the group consisting of ethylene glycol, propylene glycol, andcombinations thereof and (2) 1,4-butanediol are removed and collected ina vessel in step (b). In another embodiment, in step (b), 1,4-butanediolis refluxed back into the reactor and a component selected from thegroup of excess butanediol, ethylene glycol, propylene glycol,tetrahydrofuran, and combinations thereof is removed. In anotherembodiment, the diol component selected from the group consisting ofethylene glycol, propylene glycol, and combinations thereof and1,4-butane diol are separated and the 1,4-butanediol is refluxed backinto the reactor in step (b).

Step (b) is practiced for a sufficient period of time to reduce at least65% of ethylene glycol from the second molten mixture. The duration ofstep (b) can also vary. In one embodiment, step (b) lasts at least 45minutes to several hours, or more. The pressure at which step (b) iscarried out can vary. In one embodiment, wherein step (b) is carried outin atmospheric conditions. In another embodiment, step (b) is carriedout in subatmospheric conditions. In another embodiment, step (b) iscarried out with excess 1,4-butanediol and at a pressure ranging from 30to 150 kPa absolute. Different combinations are possible. In oneembodiment, step (b) is carried out with excess 1,4-butanediol and at apressure ranging from 300 to 1500 mbar absolute. In another embodiment,1,4-butanediol is used in a molar excess amount ranging from 1.1 to 5.

Step (c) of the three step embodiment can also be carried out withmodifications, depending on the application. In one embodiment, forinstance, a component selected from the group of excess butanediol,ethylene glycol, propylene glycol, tetrahydrofuran, and combinationsthereof is removed during step (c). The pressure at which step (c) iscarried out can also vary. In one embodiment, step (c) is carried out ata pressure that is less than 10 mbar. In another embodiment, step (c) iscarried out at a pressure that is less than 1.0 mbar.

The three step process can be carried out in the same reactor.Alternatively, the three step process can be carried out in at least tworeactors.

In another embodiment, the three step process can include the step ofadding a basic compound during step (a), step (b), step (c), andcombinations thereof, and thereby further reduce THF production. Thebasic compound, as in the two step embodiment, can contain an alkali oralkaline earth metal or aluminium compound and can be selected from oneor more of the following compounds sodium alkoxides, sodium hydroxide,sodium acetate, sodium carbonate, sodium bicarbonates, potassiumalkoxides, potassium hydroxide, potassium acetate, potassium carbonate,potassium bicarbonate lithium alkoxides, lithium hydroxide, lithiumacetate, lithium carbonate, lithium bicarbonate, calcium alkoxides,calcium hydroxide, calcium acetate, calcium carbonate, calciumbicarbonates, magnesium alkoxides, magnesium hydroxide, magnesiumacetate, magnesium carbonate, magnesium bicarbonates, aluminiumalkoxides, aluminium hydroxide, aluminium acetate, aluminium carbonate,aluminum bicarbonates, and combinations thereof.

The amount of the basic compound used is generally at least 0.1 ppm. Inone embodiment, the amount of the basic compound is from 0.1 to 50 ppm.In another embodiment, the amount of the basic compound ranges from 1 to10 ppm.

The addition of the basic compound such as an alkali metal compound canreduce the amount of total THF production, as compared to when theprocess is carried out without the basic compound. In one embodiment,the total THF produced during the process is reduced by at least 10%, ascompared to a process that does not use the basic compound. In anotherembodiment, the total THF produced during the process is reduced rangesfrom at least 10% to 50%, or more. In another embodiment, the THF isreduced from at least 10% to 50%. Advantageously, the invention includesan embodiment in which the 1,4-butanediol is derived from biomass. Inone embodiment, the biomass is a grain selected from the groupconsisting of corn, wheat, and combinations thereof.

In this embodiment, the 1,4-butanediol is used as described above. Whenthis embodiment is used, articles can further reduce the use of CO₂emissions that are ordinary generated when 1,4-butanediol is made frommonomers.

Advantageously the three step process can reduce tetrahydrofuran by anamount that is at least 30% as compared to the amount of tetrahydrofuranproduced by a process that depolymerizes polyethylene terephthalatecomponent with 1,4-butanediol instead of the diol component selectedfrom the group consisting of ethylene glycol, propylene glycol, andcombinations thereof.

The process for making the PET-derived modified PBT may contain anadditional step in which the PBT formed from the molten mixture issubjected to solid-state polymerization. Solid-state polymerizationgenerally involves subjecting the PBT formed from the molten mixture toan inert atmosphere and heating to a temperature for a sufficient periodof time to build the molecular weight of the PBT. Generally, thetemperature to which the PBT is heated is below the melting point of thePBT, e.g., from 5 to 60° C. below the melting point of the PBT. In oneembodiment, such a temperature may range from 150 to 210° C. Suitableperiods of time during which the solid-state polymerization occurs mayrange from 2 to 20 hours, depending on the conditions and equipment. Thesolid-state polymerization is generally carried out under tumultuousconditions sufficient to promote further polymerization of the PBT to asuitable molecular weight. Such tumultuous conditions may be created bysubjecting the PBT to tumbling, the pumping of inert gas into the systemto promote fluidization of polymer particle, e.g., pellets, chips,flakes, powder, and the like. The solid-state polymerization can becarried out at atmospheric pressure and/or under reduced pressure, e.g.from 1 atmosphere to 1 mbar.

Remarkably, despite having residues derived from polyethyleneterephthalate, e.g., ethylene glycol and isophthalic acid groups (groupsthat have long been regarded as undesired components in virgin PBT), thePET-derived modified PBT component exhibits useful properties. It isimportant to be aware that the PET derived PBT compositions of theinvention are not “recycled,” as the term is ordinarily used. That is,the compositions are not reprocessed PBT or PET. Rather, they areentirely new materials made from PET, a material that is fundamentallydifferent from PBT. Also, the PET-derived modified PBT is structurallydifferent from “virgin” PBT. Virgin PBT, for instance, is a non-randomhomopolymer. The modified PBT of this invention is a random copolymer.The physical properties of the PET-derived modified PBT will now bediscussed.

The physical properties of the PET-derived modified PBT component canvary, depending on factors such as the performance properties that arerequired, the equipment used, process parameters, and the like. Theintrinsic viscosity (IV) of the PET-derived modified PBT is at least0.56 dL/g. In another embodiment, the intrinisic viscosity ranges from 1to 1.3 dL/g. In another embodiment, the intrinsic viscosity ranges from0.95 to 1.05 dL/g. All intrinsic viscosities in this application referto those viscosities measured in a solution of 60 wt. % phenol and 40wt. % 1,1,2,2-tetrachloroethane at 25° C.

The melting point of the PET-derived modified PBT is at least about 200°C. or 210° C. In another embodiment, the melting point ranges from 204°C. to 218° C. In another embodiment, the melting point ranges from 211°C. to 223° C. The crystallization temperature of the PET-derivedmodified PBT is at least 150° C. In another embodiment, thecrystallization temperature ranges from 162° C. to 175° C. In anotherembodiment, the crystallization temperature ranges from 164° C. to 178°C.

The flexural modulus of the PET-derived modified PBT is at least 1000MPa. In another embodiment, the flexural modulus ranges from 1000 MPa to5000 MPa. In another embodiment, the flexural modulus ranges from 2400to 2500 MPa. The tensile strength (@yield) of the PET-derived modifiedPBT is at least 30 MPa. In another embodiment, the tensile strengthranges from 30 MPa to 100 MPa. In another embodiment, the tensilestrength ranges from 51 to 53 MPa. The tensile elongation (@yield) ofthe PET-derived modified PBT is at least 2%.

In another embodiment, the tensile elongation (yield, break) ranges from2% to 10%. In another embodiment, the tensile elongation (@yield) rangesfrom 3 to 3.3%. The heat deflection temperature of the PET-derivedmodified PBT generally ranges from at least 45 of 60° C. at 1.82 MPa for3.2 mm bars. In another embodiment, the heat deflection temperatureranges from 45° C. to 65 or 75° C. In another embodiment, the heatdeflection temperature ranges from 60 to 70° C. The notched izodstrength temperature of the PET-derived modified PBT is at least 20 J/m.In another embodiment, the notched izod strength ranges from 20 J/m to60 J/m. In another embodiment, the notched izod strength ranges from 27to 45 J/m.

The molecular weight of the PET-derived modified PBT is generally atleast 3000 g/mol. In one embodiment, the molecular weight of thePET-derived modified PBT ranges from 18000 to 42000 g/mol. In anotherembodiment, the molecular weight of the PET-derived modified PBT rangesfrom 30000 to 42000 g/mol.

The process can further comprise increasing the molecular weight of thepolymer obtained in step (c) by subjecting the polymer formed in step(c) to solid state polymerization. When subjected to solid statepolymerization step, the molecular weight of the PET-derived modifiedPBT is generally at least 15000 g/mol. In one embodiment, the molecularweight of the PET-derived modified PBT that has been subjected to solidstate polymerization ranges from 18000 to 42000 g/mol. In anotherembodiment, the molecular weight of the PET-derived modified PBT thathas been subjected to solid state polymerization ranges from 20000 to50000 g/mol.

In addition to providing a novel process for making PBT from PET, theinvention includes embodiments directed to compositions made from such aprocess. In one embodiment, the PBT formed is a composition thatincludes a white, non-yellow, PET-derived modified PBT containingisophthalic acid and ethylene glycol groups, such that the compositionhas an intrinsic viscosity that is at least 0.55 dL/g or more than 0.55dL/g and the isophthalic acid and the ethylene glycol are present in anamount that is more than 0.85 wt. %. The intrinsic viscosity can varyand, advantageously, the process makes it possible to make polymers witha wide range of higher intrinsic viscosities, e.g., from 0.55 to 1.3dL/g, or 1.5 dL/g or higher. In another embodiment, compositions made byour process can contain ethylene glycol is present in an amount rangingfrom 0.1 wt. % to 2 wt. %.

In use, a polyethylene polyethylene terephthalate component selectedfrom the group consisting of polyethylene terephthalate and polyethyleneterephthalate copolymers reacts with a diol component selected from thegroup consisting of ethylene glycol propylene glycol, and combinationsthereof, in a reactor at a pressure that is at least atmosphericpressure in the presence of a catalyst component at a temperatureranging from 190° C. to 250° C., under an inert atmosphere, underconditions sufficient to depolymerize the polyethylene terephthalatecomponent into a first molten mixture containing components selectedfrom the group consisting of oligomers containing ethylene terephthalatemoieties, oligomers containing ethylene isophthalate moieties, oligomerscontaining diethylene terephthalate moieties, oligomers containingdiethylene isophthalate moieties, oligomers containing trimethyleneterephthalate moieties, oligomers containing trimethylene isophthalatemoieties, covalently bonded oligomeric moieties containing at least twoof the foregoing moieties, ethylene glycol, propylene glycol andcombinations thereof; wherein the polyethylene terephthalate componentand the diol component are combined under agitation. It will beappreciated that our invention includes embodiments in which thepolyethylene polyethylene terephthalate component is depolymerized with1,4-butane diol. In one embodiment, the polyethylene terephthalatecomponent can be depolymerized with mixtures of 1,4-butane diol andethylene glycol.

1,4-butanediol is then added to the first molten mixture in a reactor inthe presence of a catalyst component at a temperature ranging from 190°C. to 240° C., under conditions that are sufficient to form a secondmolten mixture containing a component selected from the group consistingof oligomers containing ethylene terephthalate moieties, oligomerscontaining ethylene isophthalate moieties, oligomers containingdiethylene terephthalate moieties, oligomers containing diethyleneisophthalate moieties, oligomers containing trimethylene terephthalatemoieties, oligomers containing trimethylene isophthalate moieties,oligomers containing butylene terephthalate moieties, oligomerscontaining butylene isophthalate moieties, covalently bonded oligomericmoieties containing at least two of the foregoing moieties,1,4-butanediol, propylene glycol, ethylene glycol, and combinationsthereof.

Temperature is then increased the temperature of the second moltenmixture under subatmospheric conditions and agitation to a temperaturefrom 240° C. to 260° C., thereby forming a modified random polybutyleneterephthalate copolymer containing at least one residue derived from thepolyethylene terephthalate component.

In another embodiment, a suitable amount of a polyethylene terephthalatereacts with an excess amount of a diol component selected from the groupof ethylene glycol, 1,4-butane diol, and combinations thereof, at apressure that is at least atmospheric pressure in the presence of acatalyst component at a temperature ranging from 180° C. to 230° C. Asuitable inert atmosphere is selected and the conditions are such thatthe polyethylene terephthalate depolymerizes into a first molten mixturecontaining components selected from the group consisting of oligomerscontaining ethylene terephthalate moieties, oligomers containingethylene isophthalate moieties, oligomers containing diethyleneterephthalate moieties, oligomers containing diethylene isophthalatemoieties, oligomers containing trimethylene terephthalate moieties,oligomers containing trimethylene isophthalate moieties, covalentlybonded oligomeric moieties containing at least two of the foregoingmoieties, ethylene glycol, propylene glycol and combinations thereof.

The polyethylene terephthalate component and the added diol such as1,4-butanediol are combined in the liquid phase under agitation and theadded diol such as 1,4-butanediol is continuously refluxed back into thereactor during this step. If the added diol is different from1,4-butanediol, this step is preferably modified to include the step ofremoving the added diol under reduced pressure followed by incorporationof 1,4-butanediol into the reaction mixture. When the molten mixture hasformed, the molten mixture is subjected to subatmospheric pressure andthe temperature of the system increases to a temperature ranging from250° C. to 260° C., and thereby forming a PET-derived modified PBTcomponent containing the isophthalic acid groups and ethylene glycolgroups integrated into its backbone. Excess butanediol, ethylene glycol,and THF are removed during step (b) step (b) is carried out underagitation.

The steps of the process can be carried out in the same reactor. In oneembodiment, however, the process is carried out in two separatereactors, where step (a) is carried out in a first reactor and when themolten mixture has formed, the molten mixture is placed in a secondreactor and step (b) is carried out.

The amounts of PET-derived modified PBT that can be made from theinvention can vary with factors such as production needs, equipment,available materials, and the like. Nonetheless, the invention containsembodiments in which the amounts are sufficiently high for variouscommercial applications. In one embodiment, the process produces atleast 200 kilograms PET-derived modified PBT/per hour. In anotherembodiment, the process can produce from 500 to 1000 kilogramsPET-derived modified PBT/per hour. In another embodiment, the processcan from produce from 1000 to 2000 kilograms PET-derived modifiedPBT/per hour.

Although the foregoing description has been directed to processes formaking modified PBT materials from PET, and respective processes formaking such materials, the scope of the invention includes processes formaking polyesters other than PBT from PET. Examples of other polyestersinclude polycyclohexane terephthalate glycol (PCTG) polycyclohexaneterephthalate (PCT), polyethylene terephthalate glycol, (PETG);polytrimethylene terephthalate (PTT), poly-xylylene terephthalate (PXT),polydianol terephthalate (PDT).

As such, in one embodiment, the invention includes a process for makingPTT that involves the steps of

(a) reacting (i) a polyethylene terephthalate component with (ii) a1,3-propanediol at a pressure that is at least atmospheric pressure inthe presence of a catalyst component at a temperature ranging from 180°C. to 260° C., under an inert atmosphere, thereby depolymerizing thepolyethylene terephthalate component into a molten mixture containingpolyethylene terephthalate oligomers, polypropylene terephthalateoligomers, 1,3-propanediol, and ethylene glycol;

wherein the polyethylene terephthalate component and the 1,3-propanediolare combined in the liquid phase under agitation and the 1,3-propanediolis refluxed back into the reactor during step (a);

(b) subjecting the molten mixture to subatmospheric pressure andincreasing the temperature of the molten mixture to a temperatureranging from 240° C. to 270° C., and thereby forming a PET-derived PTTcomponent selected from one or more of the following groups:

wherein R′ is a terephthalic acid group (-1,4-(C₆H₄)—);

R″ is an isophthalic acid group (-1,3-(C₆H₄)—);

D is a divalent propylene radical (—(C₃H₆)—); and

D′ is a divalent ethylene radical (—C₂H₄)—);

wherein excess propanediol and ethylene glycol are removed during step(b) and wherein step (b) is carried out under agitation.

The invention provides previously unavailable advantages. For instance,the invention provides a process that is relatively simple and effectiveat producing relatively large amounts of PET-derived modifiedpolyesters, such as modified PBT efficiently. The process of theinvention requires specific conditions found to be critical for avoidingdisadvantages of processes disclosed in the prior art.

Further, the process for making the PET-derived random, modified PBTcopolymers can advantageously substantially reduce carbon dioxideemissions and solid waste. Since the PET-derived polyester randommodified PBT copolymers made by the inventive process are made fromscrap PET and not monomers, the process significantly reduces the amountof carbon dioxide emissions and solid waste. Carbon waste reduction (orcrude oil savings) occurs because the carbon that constitutes thedimethyl terephthalate or terephthalic acid ordinarily used to makepolyesters is not used. Instead, rather a PET component, e.g., polyesterscrap, is used. The process to make DMT or TPA from crude oil is highlyenergy intensive and as a result, substantial emissions of CO₂ to theatmosphere occur from burning of non-renewable energy sources. By notusing DMT or TPA to make the PET derived PBT, carbon dioxide emissionssavings are obtained. In one embodiment, the process for makingPET-derived modified PBT can eliminate at least 1 kg of CO₂ emissionsfor every kilogram of PET-derived modified PBT made with the process, ascompared to a process that makes virgin PBT homopolymers from monomers.In another embodiment, the process for making PET-derived modified PBTcan eliminate from 1 kg to 1.5 kg, or more CO₂ emissions for everykilogram of PET-derived modified PBT made with the inventive process, ascompared to a process that makes virgin PBT homopolymers from monomers.Additionally, there are energy savings/reduced carbon dioxide emissionswhen the ethylene glycol byproduct is recovered and used instead ofordinary ethylene glycol in manufacturing.

Additionally, when the source of BDO is a biomass derived feedstock suchas succinic acid, the carbon dioxide savings are further increased fortwo reasons. Bio derived succinic acid is made form sugars or other bioderived hydrocarbons that are derived from atmospheric carbon vs fossilfuel carbon sources. This reduces the environmental impact of thepolymer derived from BDO based on succinic acid from biomass sources.Furthermore, the fermentation to yield succinic acid requires carbondioxide as an input thus leading to further carbon dioxide reductions.

Advantageously, a modified polybutylene terephthalate random copolymercan have a reduced CO₂ emissions index. The reduced CO₂ emissions index,as defined in this application, is the amount of CO₂, expressed in kg,that is saved when one (1) kg of a composition containing the modifiedpolybutylene terephthalate random copolymers is made, as compared to theamount of CO₂ expressed in kg, that is created when the composition ismade with polybutylene terephthalate that is derived from monomers.Generally, the modified PBT random copolymers have a reduced CO₂emissions index that is more than approximately 1.3 kg, and can rangefrom 1.3 kg to 2.5 kg.

The basis for this feature is discussed below. The difference betweenthe amount of CO₂ that is created during ordinary processes for makingvirgin, monomer-derived PBT and the process for making 1 kg of themodified polybutylene terephthalate random copolymers can range from 1.3kg to 2.5 kg, or more suitably from 1.7 kg to 2.2 kg. It should be notedthat this difference is based on calculations for the entire processthat starts from crude oil to the monomers to the PBT versus scrap PETto oligomers to the modified PBT. In other words, the process for making1 kg of the modified polybutylene terephthalate random copolymerscreates 1.3 to 2.5 kilograms less CO₂ as compared to the process formaking 1 kg of virgin PBT from crude oil.

These results can be derived and verified by using material and energybalance calculations (calculations that are well known in the chemicalengineering art) and comparing the amount of energy used to makemodified PBT random copolymers from PET and the amount of energy used tomake PBT from terephthalic acid or dimethyl terephthalate.

The invention is further described in the following illustrativeexamples in which all parts and percentages were by weight unlessotherwise indicated.

Examples 1-9

The overall quantity of individual materials taken and the reactionscale used are indicated in Table 1.

TABLE 1 Amounts of raw materials taken and reaction scale for Examples1-9¹ Scale of Overall ratio of Depolymerization stageTransesterification stage reaction principal raw materials EG PET BDOExample PBT amount EG:PET BDO:PET taken taken Catalyst taken Catalyst,Ti Cocatalyst no. prepared (g) mole ratio mole ratio (g) (g) (ppm) (g)(ppm) (ppm) 1 8000 1.27 3.6 2800 7000 No added 11800 (100) — catalyst 28000 1.27 3.6 2800 7000 Sb (100) 11800 (50 + 50)* — 3 8000 1.5 3.6 34007000 Ti (50) 11800 (50 + 50)* — 4 8000 1.5 2.4 3400 7000 Ti (50) 8000(50 + 50)* — 5 234.2 1.5 3.6 95.9 204.1 Ti (50) 344.4 (100) — 6 234.21.5 3.6 95.9 204.1 Ti (50) 344.9 (100) — 7 234.2 1.5 3.6 95.9 204.1 Ti(50) 344.4 (100) — 8 234.2 1.5 3.6 95.9 204.1 Ti (50) 344.3 (100) NaOMe(13.8) 9 234.2 1.5 3.6 95.9 204.1 Ti (50) 344.1 (100) NaOMe (13.8) ¹Noadditional ingredient was added at the polymerization stage. *Thecatalyst is added in two parts- first part at atm. pressure and thesecond part at 80 kPa

Green colored PET scrap from bottles was obtained from a commercialsource. In the scrap cleaning process, the PET scrap was cleanedmanually involving first a hot water wash followed by manual sorting toseparate colored bottles and PVC bottles, crushing, hydrofloatation toseparate PP, labels, caps etc., alkali wash to remove glue, and finallya demineralized water wash to remove alkali followed by drying. Theresulting PET flakes were used as the main raw material in thedepolymerization step. The post consumer recycle PET flakes had an ivspecification of 0.68 to 0.78 dl/g and a melting point specification of245° C. to 255° C. The PVC content was less than 10 ppm byspecification. The butanediol was obtained from BASF and had a purityspecification of >99.5 wt. %. The ethylene glycol was obtained fromMerck Co. and had a purity specification of >99.5 wt. % The TPT catalystused was the commercial Tyzor grade available from Dupont.

Depolymerization (Glycolysis) with Ethylene Glycol—Preparation of FirstMixture

Depolymerization of PET flakes was carried out at a mole ratio of PET(‘mer’ repeat unit) to EG in the range of 1:0.8 to 1:2.0 to make thedepolymerization product. The reaction was conducted in the presence ofcatalyst (titanium, antimony or tin compounds (range from 50 to 125ppm)). The process was carried out under a pressure in the range 1.0 bar−6 bar and at a temperature of 200 Deg C. to 260 Deg C.). The total timeof depolymerization was in the range from 20 to 120 min and preferably30 to 100 min. This is further followed by filtration of the mass toremove black specs and other insoluble impurities. The resulting masswas called the first mixture. The depolymerization reaction conditionsemployed for examples 1-9 are presented in Table 2.

TABLE 2 Process Conditions for Depolymerization with ethylene glycolExample Pressure Depolymerization No. (kPa) ° C. time (min) 1 350 230 302 350 232 65 3 350 232 95 4 350 230 95 5 350 235 90 6 350 235 90 7 350235 90 8 350 235 90 9 350 235 90

Transesterification—Preparation of Second Mixture (at AtmosphericPressure)

Transesterification was done by reacting the first mixture with BDO withor without cocatalyst. The cocatalyst in some of the examples was sodiummethoxide of (10-14 ppm). The BDO was taken in excess over thestoichiometric requirement and the mole ratio of excess tostoichiometric requirement ranged from 2.0 to 4.0. The reaction wasconducted in the presence of additional amount of catalyst (50-120 ppmof Ti, Sn or Sb catalysts or combinations thereof) at temperature rangeof 200 to 245 Deg C. and more preferably 210 to 235 Deg C. atatmospheric pressure for 10-40 min and more preferably 15-30 min. Duringthis period, the vapors were passed through a distillation columnwherein the EG and THF were removed after separation from BDO which wasrefluxed back into the reactor. This resulted in the reaction masscalled second mixture. The second mixture was not characterized and thereaction was continued as given below to form the third mixture.

Preparation of Third Mixture (at Pressures in the Range from 95 kPa to50 kPa)

In Examples 1-4, the second mixture was subjected to a pressureinitially in the range of 95 to 80 kPa for a period of 10-40 min andmore preferably 15-30 min. During this period, the temperature wascontrolled between 190 and 235 (C) and more preferably between 190 and220 deg C. and the vapors were subjected to distillation and much of theBDO of condensed vapors was refluxed back accompanied by the removal ofEG, THF and minor amounts of BDO. At this stage, 80% of total EG presentboth as free and as bound was removed by distillation duringtransesterification. Subsequently, the pressure was reduced gradually toa range from 80 to 50 kPa and the temperature was maintained between 190and 235 deg C. and more preferably between 190 and 220 deg C. The totaltime for transesterification was maintained between 30 to 150 min andpreferably between 90 to 120 min. EG, THF and minor amount of BDO wereremoved by distillation and as before, much of the BDO was continuouslyrefluxed back into the reactor. In examples 5-9, the pressure waslowered from atmospheric to 60 kPa slowly, and held at 60 kPa for aperiod from 20-150 minutes and more preferably from 30-60 minutes. Thetemperature was maintained between 190 and 235 deg C. and morepreferably between 190 and 220 deg C. and the vapors were subjected todistillation and much of the BDO of condensed vapors was refluxed backaccompanied by the removal of EG, THF and minor amounts of BDO. Thisresulted in the formation of a third mixture. The reaction conditionsemployed and the amounts of various ingredients collected in thedistillate at the end of transesterification are shown in Table 3.1

TABLE 3 Transesterification conditions Multiple Time in pressure Min forDistillate composition conditions respective QTY of from Atm to Temppressure THF WATER EG BDO OVHD Example given kPa Deg C. conditions Wt %Wt % Wt % Wt % gms 1 Atm, 50 194-222 120, 29 19.47 7.06 42.87 30.6010222 2 Atm, 80, 50 193-223 75, 30, 30 18.91 8.14 42.79 30.16 8364 3Atm, 80, 50 193-221 60, 30, 30 13.34 4.76 47.67 34.23 10324 4 Atm, 80,50 191-219 65, 30, 30 14.38 7.18 56.36 22.08 8430 5 60 194-217 60 18.294.85 48.92 27.95 302.04 6 60 194-218 45 9.48 4.35 48.44 37.73 227.12 760 196-203 30 6.08 2.96 52.04 38.93 197.11 8 60 193-214 30 3.51 3.7152.43 40.36 240.72 9 60 193-217 45 4.84 3.34 46.48 45.34 252.36

Recycling the BDO enables a favorable BDO to EG ratio in thetransesterification reactor, and improves productivity by lowering thetransesterification time. EG wass reused in the depolymerization stepand BDO was reused in the transesterification step. The THF and watermixture were sent to storage vessels.

Polycondensation

Polycondensation using the third mixture was done at a temperature inthe range from 230 to 265 Deg C. and preferably 245 to 255 Deg C. Thepressure was gradually reduced to a level of 0.01 kPa to 1 kPa to enablemolecular weight build-up. The reaction was conducted within a time spanof 45 to 120 min and preferably 45 to 75 min. During polycondensation,excess BDO and residual EG was removed, along with THF and Water. Thevapor byproducts were subjected to distillation to separate EG, BDO, THFand water mixture. The final polymer product (PBT) had an I.V. rangingin between 0.5 and 1.5 dl/gm and EG and DEG content less than 0.4 wt. %each based on final polymer. Typically, the IPA content was less than 2%in the polymer. The melting point of the final polymer was in the rangeof 215 to 222 Deg C. The experimental conditions used forpolycondensation and the composition of the distillates are shown inTable 4.

TABLE 4 Polycondensation Reaction conditions Overhead Distillatecomposition Qty of Pressure Temp Time THF Water Overhead Example rangekPa Deg C. min Wt % Wt % EG Wt % BDO Wt % (g) 1 50-0.13 253 84 2.5782.87 15.76 78.79 2980 2 50-0.11 253 87 0.496 1.4 13.69 84.42 5270 350-0.11 253 75 1.863 2.34 16.26 79.54 2756 4 50-0.13 252 63 1.755 6.0730.72 61.45 1634 5 60-0.05 255 60 4.312 11.220 5.542 78.925 115.15 660-0.08 255 90 3.799 3.323 16.075 76.803 132.13 7 60-0.04 254 75 3.1823.116 23.397 70.305 204.7 8 60-0.06 254 75 2.353 3.578 16.811 77.257166.18 9 60-0.05 255 90 1.794 5.197 22.665 70.343 153.98Table 5 provides the data on the composition of the polymers obtainedthrough ¹H NMR analysis for examples 1-9.

Comparative Examples C. Ex. 1 and C. Ex. 2

Comparative examples C. Ex. 1 and C. Ex. 2 are repeat experimentscarried out based on the process disclosed in the prior art, U.S. Pat.No. 5,451,611 assigned to CSIR. In '611 patent the distinction betweendepolymerization step and transesterification was not made. The quantityof materials used and process conditions employed are shown in Tables5(a) and 5(b).

TABLE 5(a) and 5(b) Materials and process conditions employed for C. Ex.1 and C. Ex. 2. Transesterification PBT PET BDO Catalyst TE TE TEComparative Qty Taken taken (Ti) Cocatalyst Press Temp Time ExampleBDO:PET gms Gms gms ppm ppm kPa Deg C. min C. Ex. 1 2.95 10000 834011550 Ti 100 — atm, 50 200-226 255, 30 C. Ex. 2 2.95 10000 8340 11550 Ti100 — atm, 50 198-225 245, 30

TABLE 5(b) Polycondensation Press Temp Time kPA Deg C. min 50-0.12 25483 50-0.11 254 84

TABLE 6 Composition of the PBT derived from PET resin (NM = notmeasured) Isophthalic Terephthalic Groups Groups BDO DEG groups EGgroups Na Sb Sn Ti Residue Ex, Mole % Mole % Mole % Mole % Mole % ppmppm ppm ppm Equivalents** 1 1.14 48.88 48.88 0.24 0.86 1107.6 152.4157.4  97.4 4.5 2 1.24 48.67 49.03 0.36 0.70 NM NM NM NM 4.6 3 1.1448.75 49.12 0.24 0.73 1138.9 140.3 125.1 101.1 4.2 4 1.20 48.26 47.890.19 2.46 NM NM NM NM 7.7 5 1.23 48.59 49.26 0.06 0.86 NM NM NM NM 4.3 61.13 49.04 49.10 0.12 0.61 1535.0 130.7 130.5  74.8 3.7 7 1.36 48.9048.48 0.18 1.08 NM 203.8 235.6 111.8 4.6 8 1.06 48.73 48.98 0.24 0.98 NM156.5 176.6  93.1 4.6 9 1.38 48.64 48.88 0.12 0.98 NM  95.1 115.8 167.55.0 C. Ex. 1. 1.41 48.68 47.16 0.29 2.46 — — — — 8.3 C. Ex. 2. 1.4648.66 46.36 0.29 3.23 — — — — 10 **Residual Equivalents relative to thetotal of 100 equivalents of diol and 100 equivalents of diacid groups((isophthalic acid groups + DEG groups + EG groups) × 2)

Example 4 also had a higher mole % of EG incorporated than any of theother examples as seen in Table 6. As seen in Table 1, for the example4, the BDO:PET ratio was 2.4, whereas for the examples 5-9 as well asexamples 1-3, the BDO:PET ratio employed was 3.6. Mole % are expressedon the base of a total of 50 mole % for the total diol portion and 50mole % for the total diacid content of the polymer.

TABLE 7 THF amount formed Example PBT prepared, g THF formed, g Ratio of(THF/PBT) as % 1 8000 2067 25.84 2 8000 1608 20.10 3 8000 1429 17.86 48000 1241.0 15.51 5 234.2 60.2 25.70 6 234.2 26.5 11.32 7 234.2 18.57.90 8 234.2 12.4 5.29 9 234.2 15.0 6.40 C. Ex. 1. 10000 4190 41.90 C.Ex. 2. 10000 4355 43.55

The examples, as per Table 7 show that the process is versatile and canproduce modified polybutylene terephthalate copolymers at different THFproduction levels. The process of the invention enables production ofmuch lesser formation of THF than the comparative examples C. Ex. 1 andC. Ex. 2 (see Table 7). Also, Examples 8 and 9 where sodium methoxideadditive was used, the THF amount formed was the lowest % relative tothe amount of PBT made. Also from the examples 1-9, a lower % of THF wasformed wherever the time of transesterification as shown in Table 3 waslower.

TABLE 8 Differential scanning calorimetry, viscosity and molecularweight Characterization data for the examples 1-9 and comparativeexamples C. Ex. 1 and C. Ex. 2 DSC Analysis DH DH Viscosity MolecularWeight Tm Tc fusion cryst IV Mn Mw PDI Example Deg C. Deg C. kJ/kg kJ/kgdl/gm Daltons Daltons Daltons 1 220.79 176.5 37.26 47.26 0.803 2418063719 2.64 2 221.45 178.78 29.69 39.41 0.798 24221 62776 2.59 3 221.1180.99 28.73 39.31 0.805 24495 63277 2.58 4 217.26 171.58 27.28 36.540.794 24006 63791 2.66 5 220.42 186.13 38.34 49.47 0.720 31850 681682.14 6 220.42 184.86 32.03 43.13 0.710 24675 79596 3.23 7 219.16 183.6435.51 42.51 0.740 29505 77380 2.62 8 220.45 184.76 35.68 44.18. 0.69025053 80788 3.22 9 220.47 183.98 35.54 43.99 0.720 22609 78916 3.49 C.Ex. 1 214.42 170.19 31.33 40.85 0.787 22877 62481 2.73 C. Ex. 2 212.76169.34 27.01 37.73 0.755 20553 59986 2.92

Example 10 Solid State Polymerization

In order to get a high value of intrinsic viscosity (IV) for the PETderived PBT, a low viscosity sample from example 4 (IV=0.79) wassubjected to solid state polymerization in a tumbling reactor at 100mbar pressure at a temperature of 190-220 deg C. for about 48 to 72 h.The intrinsic viscosity was checked intermittently during the viscositybuild-up and a product with a final intrinsic viscosity value of 1.19was obtained. This example 10 is illustrative of a process for obtainingpolymer samples of PET derived PBT of high intrinsic viscosity.

Example 11 Synthesis of Butanediol from Corn Based Succinic Acid

The purpose of this example is to show that BDO can be derived frombiomass.

Techniques/Procedures

Bio-succinic acid for the experiments performed in example 19 wassourced from Diversified Natural Products.BDO from bio Succinic acid wassynthesized in a two-step process as below:

Step (1): Esterification of Succinic Acid to Diethyl Ester:

In a 2.0 litre RB flask on an oil bath with overhead stirrer andcondenser arrangement, 200 grams (1.69 m) of bio Succinic acid, 1.0litre of dry Ethyl alcohol and 5-8 drops of concentrated H₂SO₄ werecharged and heated to reflux for 8 hrs. After 8 hrs the alcohol wasdistilled off, 500 ml dichloromethane was added, and washed with 450 mlof 10% sodium carbonate solution to get distinctly alkaline pH. Theorganic layer was washed with water and then dried over anhydrous sodiumsulfate. The solvent was removed and the diester product was distilledoff under vacuum. The pure diester was collected at 140-145° C. at ˜20mm Hg pressure.

-   -   Wt of diester: 285 grams    -   Purity: >99.0% (GC)    -   Yield: 95%

Step (2): Reduction of Diester to BDO:

60 grams (2.6 moles) of clean sodium was placed in a 3 litre RB flaskfitted with condenser, overhead stirrer, thermo well and an additionfunnel. A mild nitrogen flow was maintained to the flask to keep aninert atmosphere. The nitrogen blanket was removed and a solution of 35grams (0.2 moles) of diethyl succinate in 700 ml dry ethyl alcohol wasadded from the dropping funnel, as rapidly as possible keeping thereaction under control. If necessary, external cooling may be applied tokeep the reaction under control. The reaction mass was then heated to120-130° C. for 90 minutes till all the sodium dissolved. Then thereaction mass was cooled to room temp and 25 ml of water was cautiouslyadded. The reaction mixture was refluxed for another 30 minutes to getthe unreacted ester hydrolyzed (if any) and then 270 ml concentratedhydrochloric acid was added to the cold mixture. The precipitated sodiumchloride was filtered off and the filtrate was treated with 300 gramsanhydrous potassium carbonate to free it from water. The alcoholicsolution was filtered off and the solids were washed with hot alcohol(2×100 ml), the alcohol was removed by distillation. Dry acetone(200-250 ml) was added to the residue, the solids were filtered off andthen the acetone was distilled to get the crude BDO. The crude BDO wasfurther distilled under vacuum to get pure fraction at 135-138° C. (20mm Hg pressure). The weight of BDO obtained in this experiment was 8 gmsand the yield was measured to be 45% on the basis of the amount of estercharged.

The biomass derived BDO in this Example can be used in lieu of the BDOused in the process described above.

Example 12 Synthesis of PBT from Recycle PET and BDO from Bio BasedSuccinic Acid

The purpose of this example was to show that PBT copolymers can be madefrom biomass-derived BDO.

PET (recycle) 3.5 g (18.23 mmol), ethylene glycol 1.69 g (27.26 mmol)were added to a reactor, and heated to 180° C. under nitrogenatmosphere. At 180° C., the catalyst tetraisopropylorthotitanate(TPT)200 ppm was added and heating was continued to 225-230° C. and keptfor 90 minutes. 5.6 g (62.22 mmol) of 1,4-butanediol (BDO) derived frombio Succinic acid was added to the reaction mass and continued thereaction for another 15 minutes with distilling off ethylene glycol andbutane diol from the reaction. Vacuum was applied in a stepwise mannerstarting from 700 mbar to 500, 300, 100, 75, 50, 25, 10, 5.5, 1.5 andfinally to less than 1.0 mbar. The molten reaction mass kept at 0.7 to0.5 mbar for 30 minutes and finally the polymer was drained off thereactor under nitrogen pressure.

The polyester we obtained had an IV of 0.7 dL/g, melting temperature(Tm) 215° C. The polyester had a weight average molecular weight of57517 and a number average molecular weight of 13969 (Mw/Mn=4.12). The¹H NMR of the polyester showed 96.4 mol % butane diol incorporation and3.6 mol % of residual ethylene glycol incorporation.

In all the examples above where PBT was derived from PET, the processfor making the modified polybutylene terephthalate random copolymersexhibited a reduced CO₂ emissions index that was more than one, (1)(more than 1 kg of CO₂ was reduced for every kg of modified PBTcopolymer that was made). The example of PBT made from PET and bio-basedBDO illustrates that the CO₂ impact can be further reduced by usingmonomer derived from biomass.

Examples 13 and 14

These examples prove that a mixture of diols (containing EG as one ofthe diols) can be used to depolymerize PET and then repolymerized againto form PET derived PBT copolymer.

Examples 13 and 14 Small-Scale Process Mixtures of EG and BDO

Green colored recycle PET pellets were obtained from St. Jude, asupplier in North America. The post consumer recycle PET pellets had aniv specification of 0.68 to 0.78 and a melting point specification of245 to 255 C. The butanediol was obtained from BASF and had a purityspecification of >99.5 wt. %. The TPT catalyst is the commercial Tyzorgrade available from Dupont.

The recycle PET pellets were mixed with butanediol and ethylene glycolin a 500 ml reaction kettle as per the recipe shown in Table 9. Thetemperature of the oil bath (for the reaction kettle) was ramped up from180 to 255° C. The agitator speed was set at 20 rpm. At this stage, 0.2ml of TPT catalyst was also added to the reaction mix. The reaction massachieved an equilibrium temperature (boiling point of mixture) and thediol mixture was refluxed at this temperature for 2 hours. This is knownas the PET glycolysis stage.

For the poly stage, the reflux condenser was removed and a vacuum wasapplied to the reaction kettle. The volatilized solvents were collectedin a separate condenser. The speed of the agitator was increased to 220rpm. The system pressure was brought down to 0.15 Torr (0.199 kPa) bythe vacuum pump. The polymer molecular weight increased rapidly at thisstage as was evident by the rod climbing of the molten mass. Thereaction was stopped after 20 minutes in the poly stage. About 10 gms ofthe polymer was collected from the reaction kettle for further testingand analysis. Results of tests conducted on the polymer samples includeintrinsic viscosity (iv) data, composition of the polymer by NMRanalysis and Crystallization data by DSC analysis and they are presentedin Table 10.

TABLE 9 Raw material amount details used for the Examples 13 and 14 (PETderived PBT) Parameter Unit 13 14 Polyester Reycled Virgin Type PET PETDiol:Ester 2.67:1 2.67:1 Ratio PET kgs .10 .10 Weight BDO kgs .019 .0314Weight EG Weight kgs .073 .0646 TPT as Ti ppm 174 177 element

TABLE 10 Differential scanning calorimetry (DSC), Intrinsic viscosity(IV) and composition data by NMR of the Examples 13-14 and ComparativeExample A Comparative Example A (Commercial Exam- GE PBT Example pleItem Parameter Unit 315) 13 14 DSC Data Melting Point (° C.) 222.6176.89 180.03 Crystallization (° C.) 168.3 136.49 99.32 Temp Glass (°C.) 0 47.18 49.1 Transition Temp DH fusion (° C.) 38.4 15.5023 23.441 DH(kJ/kg) 39.9 9.5049 22.033 crystallization Intrinsic Iv dl/g 1.2 0.7403.71 Viscosity Com- EG Repeat mol % 0 25.2 31.4 position Unit by NMR DEGRepeat mol % 0 0 0 analysis Unit BDO Repeat mol % 50 25.4 19.3 UnitIsophthalic mol % 0 1.1 .8 Repeat Unit Terephthalic mol % 50 48.3 48.5Repeat Unit Total 0 26.3 32.2 Comonomers Total Residual ** 0 52.6 64.4Equivalents ** Residual equivalents relative to the total of 100equivalents of diol and 100 equivalents of diacid groups

The examples above show that when the ethylene glycol, diethyleneglycol, and isophthalic acid groups in a total amount that is more than0 and less than or equal to 23 equivalents relative to the total of 100equivalents of diol and 100 equivalents of diacid groups in the modifiedpolybutylene terephthalate random copolymer, the melting temperature Tmis below the desired amount of 200° C. It is noteworthy that the Tm ofcompositions shown in Examples 1-9 is more than 200° C. when theethylene glycol, diethylene glycol, and isophthalic acid groups in atotal amount that is more than 0 and less than or equal to 23equivalents relative to the total of 100 equivalents of diol and 100equivalents of diacid groups in the modified polybutylene terephthalaterandom copolymer. These examples prove that one can tailor thecrystallinity and the melting point of the PET derived PBT based on thediol ratio used for the transesterification and the repolymerizationstage. The glycolysis stage is quite flexible since one can use any diolor mixture of diols to depolymerize the PET. In the transesterificationand the repolymerization stage, it is preferred to keep a butanediolrich environment by removing the other diols. By maintaining abutanediol rich environment, one can then obtain a PET derived PBTcopolymer with properties similar to that of virgin PBT.

Although the present invention has been described in detail withreference to certain preferred versions thereof, other variations arepossible. Therefore, the spirit and scope of the appended claims shouldnot be limited to the description of the versions contained therein.

1. A process comprising: (a) reacting a polyethylene terephthalatecomponent selected from the group consisting of polyethyleneterephthalate and polyethylene terephthalate copolymers with a diolcomponent selected from the group consisting of ethylene glycol,propylene glycol, and a combination thereof, in a reactor at a pressurethat is at least atmospheric pressure in the presence of a catalystcomponent at a temperature ranging from 190° C. to 250° C., under aninert atmosphere, under conditions sufficient to depolymerize thepolyethylene terephthalate component into a first molten mixturecontaining components selected from the group consisting of oligomerscontaining ethylene terephthalate moieties, oligomers containingethylene isophthalate moieties, oligomers containing diethyleneterephthalate moieties, oligomers containing diethylene isophthalatemoieties, oligomers containing trimethylene terephthalate moieties,oligomers containing trimethylene isophthalate moieties, covalentlybonded oligomeric moieties containing at least two of the foregoingmoieties, ethylene glycol, propylene glycol and combinations thereof;wherein the polyethylene terephthalate component and the diol componentare combined under agitation; (b) adding 1,4-butanediol to the firstmolten mixture in the reactor in the presence of a catalyst component ata temperature ranging from 190° C. to 240° C., under conditions that aresufficient to form a second molten mixture containing a componentselected from the group consisting of oligomers containing ethyleneterephthalate moieties, oligomers containing ethylene isophthalatemoieties, oligomers containing diethylene terephthalate moieties,oligomers containing diethylene isophthalate moieties, oligomerscontaining trimethylene terephthalate moieties, oligomers containingtrimethylene isophthalate moieties, oligomers containing butyleneterephthalate moieties, oligomers containing butylene isophthalatemoieties, covalently bonded oligomeric moieties containing at least twoof the foregoing moieties, 1,4-butanediol, propylene glycol, ethyleneglycol, and combinations thereof; and (c) increasing the temperature ofthe second molten mixture under subatmospheric conditions and agitationto a temperature from 240° C. to 260° C., thereby forming a modifiedpolybutylene terephthalate containing at least one residue derived fromthe polyethylene terephthalate component.
 2. The process of claim 1,wherein the at least one residue derived from the polyethyleneterephthalate component is selected from the group consisting ofethylene glycol groups, diethylene glycol groups, isophthalic acidgroups, and combinations thereof.
 3. The process of claim 1, wherein theleast one residue derived from the polyethylene terephthalate componentis selected from the group consisting of antimony-containing compounds,germanium-containing compounds, titanium-containing compounds,cobalt-containing compounds, tin-containing compounds, aluminum,aluminum salts, 1,3-cyclohexane dimethanol isomers, 1,4-cyclohexanedimethanol isomers, alkaline earth metal salts, alkali metal salts,phosphorous-containing compounds, phosphorous-containing anions,sulfur-containing compounds, sulfur-containing anions, naphthalenedicarboxylic acids, 1,3-propanediol groups, and combinations thereof. 4.The process of claim 1, wherein the diol component selected from thegroup consisting of ethylene glycol, propylene glycol, and a combinationthereof is present in step (a) at a molar amount that is at least 25% ofthe amount of ethylene glycol moieties present in the polyethyleneterephthalate component.
 5. The process of claim 1, wherein the1,4-butanediol is added in step (b) in a molar amount that is in atleast 1.2 times molar excess relative to the molar amount of1,4-butanediol moieties incorporated into the modified polybutyleneterephthalate component obtained in step (c).
 6. The process of claim 1,wherein the diol component selected from the group consisting ofethylene glycol, propylene glycol, and a combination thereof and1,4-butanediol are separated and the 1,4-butanediol is refluxed backinto the reactor in step (b).
 7. The process of claim 1, wherein (1) thediol component selected from the group consisting of ethylene glycol,propylene glycol, and a combinations thereof and (2) 1,4-butanediol areremoved and collected in a vessel in step (b).
 8. The process of claim1, wherein, in step (b), 1,4-butanediol is refluxed back into thereactor and a component selected from the group consisting of excess1.4-butanediol, ethylene glycol, propylene glycol, tetrahydrofuran, andcombinations thereof is removed.
 9. The process of claim 1, wherein step(b) is practiced for a sufficient period of time to remove at least 65%of the ethylene glycol from the second molten mixture.
 10. The processof claim 1, wherein, a component selected from the group consisting ofexcess 1,4-butanediol, ethylene glycol, propylene glycol,tetrahydrofuran, and combinations thereof is removed during step (c).11. The process of claim 1, wherein depolymerization of the polyethyleneterephthalate component is carried out for at least 25 minutes.
 12. Theprocess of claim 1, wherein step (b) lasts at least 45 minutes.
 13. Theprocess of claim 1, wherein step (b) is carried out with excess1,4-butanediol and at a pressure ranging from 30 to 150 kPa absolute.14. The process of claim 1, wherein step (c) is carried out at apressure that is less than 1.0 mbar.
 15. The process of claim 1, whereinthe process comprising steps (a), (b), and (c) is carried out in thesame reactor.
 16. The process of claim 1, wherein the process comprisingsteps (a), (b), and (c) is carried out in at least two reactors.
 17. Theprocess of claim 1, wherein the modified polybutylene terephthalateproduced from the process has an intrinsic viscosity that is at least0.55 dL/g.
 18. The process of claim 1, wherein in step (b),1,4-butanediol is used in a molar excess amount ranging from 1.1 to 5.19. The process of claim 1, wherein the process further comprisesincreasing the molecular weight of the polymer obtained in step (c) bysubjecting the polymer formed in step (c) to solid state polymerization.20. The process of claim 1, wherein the process reduces tetrahydrofuranby an amount that is at least 30% as compared to the amount oftetrahydrofuran produced by a process that depolymerizes polyethyleneterephthalate component with 1,4-butanediol instead of the diolcomponent selected from the group consisting of ethylene glycol,propylene glycol, and a combination thereof.
 21. The process of claim 1,wherein the ratio of tetrahydrofuran formed to poly(butyleneterephthalate) formed expressed as percent is less than or equal to25.84%.
 22. The process of claim 1, wherein step (b) is carried out inatmospheric conditions.
 23. The process of claim 1, wherein step (b) iscarried out in subatmospheric conditions.
 24. The process of claim 1,wherein the 1,4-butanediol is derived from biomass.
 25. The process ofclaim 24, wherein the biomass is a grain
 26. The process of claim 24,wherein the biomass is a cellulosic material.
 27. The process of claim1, wherein the modified polybutylene terephthalate prepared from theprocess has a CO₂ reduction index that is more than 1 kg.
 28. Theprocess of claim 1, wherein the polyethylene terephthalate component isdepolymerized with ethylene glycol and the first molten mixture containsoligomers containing ethylene terephthalate moieties, oligomerscontaining ethylene isophthalate moieties, oligomers containingdiethylene terephthalate moieties, oligomers containing diethyleneisophthalate moieties, covalently bonded oligomeric moieties containingat least two of the foregoing moieties, and ethylene glycol.
 29. Theprocess of claim 1, wherein the polyethylene terephthalate component isdepolymerized with propylene glycol and the first molten mixturecontains oligomers containing ethylene terephthalate moieties, oligomerscontaining ethylene isophthalate moieties, oligomers containingdiethylene terephthalate moieties, oligomers containing diethyleneisophthalate moieties, oligomers containing trimethylene terephthalatemoieties, oligomers containing trimethylene isophthalate moieties,covalently bonded oligomeric moieties containing at least two of theforegoing moieties, ethylene glycol, propylene glycol and combinationsthereof.
 30. The process of claim 1, wherein the modified polybutyleneterephthalate made by the process contains more than 0 and less than orequal to 23 equivalents of a residue selected from the group consistingof isophthalic acid groups, ethylene glycol groups, diethylene glycolgroups, and combinations thereof, relative to the total of 100equivalents of diol and 100 equivalents of diacid groups in the modifiedpolybutylene terephthalate.
 31. The process of claim 1, wherein themodified polybutylene terephthalate made by the process containsinorganic residues derived from the polyethylene terephthalate presentin an amount from more than 0 ppm and up to 1000 ppm, and wherein theinorganic residues are selected from the group consisting ofantimony-containing compounds, germanium-containing compounds,titanium-containing compounds, cobalt-containing compounds,tin-containing compounds, aluminum, aluminum salts, alkali metal salts,alkaline earth metal salts, calcium salts, magnesium salts, sodiumsalts, potassium salts, phosphorous-containing compounds and anions,sulfur-containing compounds and anions, and combinations thereof. 32.The process of claim 1, wherein the polyethylene terephthalate componentis depolymerized with 1,4-butanediol.
 33. The process of claim 1,wherein the polyethylene terephthalate component is depolymerized with amixture of ethylene glycol and 1,4-butanediol.
 34. The process of claim1, wherein the melting point of the polybutylene terephthalate copolymeris 215° C. to 222° C.
 35. The process of claim 1, further comprising thestep of adding a basic compound during step (a), step (b), step (c), andcombinations thereof.
 36. The process of claim 35, wherein, the basiccompound is an alkali metal or alkaline earth metal salt, or analuminium compound.
 37. The process of claim 35, wherein the basiscompound is selected from the group consisting of sodium alkoxides,sodium hydroxide, sodium acetate, sodium carbonate, sodium bicarbonates,potassium alkoxides, potassium hydroxide, potassium acetate, potassiumcarbonate, potassium bicarbonate, lithium alkoxides, lithium hydroxide,lithium acetate, lithium carbonate, lithium bicarbonate, calciumalkoxides, calcium hydroxide, calcium acetate, calcium carbonate,calcium bicarbonates, magnesium alkoxides, magnesium hydroxide,magnesium acetate, magnesium carbonate, magnesium bicarbonates,aluminium alkoxides, aluminium hydroxide, aluminium acetate, aluminiumcarbonate, aluminum bicarbonates, and combinations thereof.
 39. Theprocess of claim 35, wherein the total THF produced during the processis reduced by at least 10%, as compared to a process that does not usethe basic compound.
 40. A composition comprising a non-yellow modifiedpolybutylene terephthalate made from the process of claim 1, wherein themodified polybutylene terephthalate has an intrinsic viscosity that ismore than 0.55 dL/g and wherein isophthalic acid and ethylene glycolgroups are present in an amount that is more than 0.85 wt. %.
 41. Thecomposition of claim 40, wherein the ethylene glycol groups are presentin an amount ranging from 0.1 wt. % to 2 wt. %.
 42. The composition ofclaim 40, wherein the 1,4-butanediol used to make the modifiedpolybutylene terephthalate is derived from biomass.
 43. The compositionof claim 40, wherein the biomass is selected from the group consistingof grains and cellulosic containing materials.
 44. The composition ofclaim 40, wherein the composition has a CO₂ reduction index that is morethan 1.3 kg.
 45. The composition of claim 40, wherein the modifiedpolybutylene terephthalate made by the process contains more than 0 andless than or equal to 23 equivalents of a residue selected from thegroup consisting of isophthalic acid groups, ethylene glycol groups,diethylene glycol groups, and combinations thereof, relative to thetotal of 100 equivalents of diol and 100 equivalents of diacid groups inthe modified polybutylene terephthalate.
 46. The composition of claim40, wherein the modified polybutylene terephthalate made by the processcontains inorganic residues derived from the polyethylene terephthalatepresent in the range from more than 0 ppm and up to 1000 ppm, andwherein the inorganic residues are selected from the group consisting ofantimony-containing compounds, germanium-containing compounds,titanium-containing compounds, cobalt-containing compounds,tin-containing compounds, aluminum, aluminum salts, alkali metal salts,alkaline earth metal salts, phosphorous-containing compounds and anions,sulfur-containing compounds and anions, and combinations thereof.